This invention is in the field of light emitting diodes ("LED"s) and other light emitting semiconductor devices. In particular, the present invention relates to arrays of LEDs or other light emitting devices.
LEDs mounted on metal lead frames to form modules are known. An example of such a module is Klinke, et al., Multiple Light Emitting Diode Module, U.S. Pat. No. 5,404,282 ("Klinke"). The LEDs in that patent are mounted on a rigid metal lead frame to form a lighting module.
Klinke has one obvious limitation. As the metal lead frame is relatively rigid, the finished module forms a two dimensional plane, limiting its mounting options in three dimensional spaces. Even if the lead frame of Klinke were made thinner and therefore more flexible, bending it to fit a three dimensional space would result in the individual LEDs transmitting light in many different directions, greatly reducing the perceived brightness of the module from any fixed observation point. For example, if the Klinke module were bent to form the tail lights of an automobile, many of the LEDs mounted on the bent lead frame would not be transmitting their light directly rearward. As the perceived rearward brightness is critical for visibility and safety, the misdirection of light from the Klinke module, if it were bent to fit these spaces, would limit the module's usefulness.
Several possible solutions to this problem have been suggested. A metal lead frame pre-formed to the desired shape, with the mounting sites for each of the LEDs carefully pre-bent to direct light in the desired direction, is one possibility. However, mounting the LEDs on the lead frame after the lead frame is bent is very difficult and not easily adapted to mass manufacturing.
Fully flexible printed circuit boards are another possibility, but they are more costly than metal lead frames, do not conduct heat nearly as well as metal lead frames, and require a support structure to maintain the desired final shape.
A LED module which can be molded to fit complex three dimensional spaces, which directs each of its light emitting components in the same direction, and is self-supporting would be an improvement to the art. The module should also be easily manufactured.